on the hook for

US /ɑn ðə hʊk fɔr/
UK /ɑn ðə hʊk fɔr/
"on the hook for" picture
1.

responsible for something, especially a debt or a difficult situation

:
After the accident, he was on the hook for all the repair costs.
If you don't pay, I'll be on the hook for the entire bill.